We have purified an enzyme from extracts of Clostridium SB4 that catalyzes a novel reaction involved in the anaerobic degradation of L- lysine: 3-keto, 5-aminohexanoate plus acetyl-coenzyme A yields 3- aminobutyryl-CoA plus acetoacetate. We plan to study the chemistry of the reaction with particular reference to the origin of the carbon atoms in the acetoacetate and the role of substrate-enzyme intermediates. The properties and specificity of the enzyme will also be examined. A second project will be the further purification of a CoA-transferase that catalyzes CoA transfer between butyryl-CoA and acetoacetate and a study of its properties, specificity and role in lysine degradation. If time permits, an attempt will be made to purify methane-forming bacteria that utilize lower fatty acids as substrates, and study their physiology and metabolism.